Chronometer for longitude



J. SHELDON.

Geographical Clock.

No. 6,877. Patented Nov. 20, 1849.

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UNITED STATES PATENT OFFICE.

JOHN SHELDON, OF MILLVILLE, NEW JERSEY.

CHRONOMETER FOR LONGI'IUDE.

Specification of Letters Patent No.

To all whom, it may concern:

Be it known that I, JOHN SHELDON, of Millville, in the county of Cumberland and State of New Jersey, have invented a new Mode of Ascertaining the Longitude VVithout the Aid of the Usual Instruments; and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the annexed drawing, making a part of this specification, which represent-s the dial-plate of an instrument containing the works whereby the indices are moved.

The speed or rate of the time-piece is supposed to beknown, the same as it is known on the chronometer. The main hands on the dial move atthe same rate that the earth revolves on its axis (however in an opposite direction), and consequently keep time with the sun.

My starting point is at Greenwich, Eng land; and my time is regulated by Greenwich-time, that is to say longitude, nothing. My dial is furnished with four indices .or hands, which are at right angles with each other, and are calculated to revolve once in every 24: hours. These hands are respectively marked: Midday, Evening, Midnight, and Morning. Near the circumference of the dial, there is one rubric containing the hour-division, and another containing the division into degrees, as shown on drawing.

The midday-hand gives the longitude at noon. WVhen you are taking the sun to get your latitude, take the minute timeof the hanging of the sun, and the time she is 6,877, dated November 20, 1849.

hanging, divide equally. Then count to the left from the middayhand, when you will obtain your true longitude at noon, in any part of the world, premising the rate of time being known to you.

2. Evening time: Knowing the length of the day, you get your longitude when the sun dips or disappears below the horizon. If the day is over 12 hours long, you count from the evening-hand to the left, when you will get your longitude at eveningtime.

3. Midnight: hen you are getting the latitude at midnight, proceed as at midday, and you will obtain your longitude.

4. Morning time: At sunrise look at the morning-hand of the dial, which will give you the longitude at that time, knowing the length of the day; if it is more than 12 hours long, count from the morning hand to the left; if less than 12 hours, count from said hand to the right.

At twilight look at the morningor evening-hand, and work the same as for morning or evening-time.

What I claim as my invention and desire to secure by Letters-Patent is The dial with four hands, which are at right angles to each other, and revolve once in 24: hours; said dial being divided into hours and degrees, substantially in the manner and for the purposes above described.

JOHN SHELDON.

lVitnesses ANDREW FINLEY, FRANCIS BENNE. 

